One of the earliest examples is Emma Bull's War for the Oaks, where the rock band has Elvish lead guitar and bass players, and a faerie roadie.

In Soul Music, everyone keeps asking Buddy (a parody of every dead rock star, ever, but especially Buddy Holly)as, you know, Buddy's real name "Imp y Celyn" translates as "Bud of the Holly." if he's elvish. (Which is worrisome for Buddy in certain kinds of company, because dwarves and trolls have a standing blood feud against elves.) At the end of the book, after he's saved from an alternate universe in which he dies in a carriage accident, someone comments that there's a new guy working in the chip shop, and she could swearhe looks elvish.

Muppet Classic Theater: The last story is "The Elves And The Shoemaker". Rizzo the Rat exclaims "A story about Elvis?". Gonzo tries to correct him, but sure enough in the story, the elves all look and act like Elvis. And they make blue suede shoes.

In the Due South episode "Gift of the Wheelman", where the robbery suspects are dressed as Santas, the police accidentally round up Elvis impersonators for questioning instead of Christmas elves.

The Magic: The Gathering card "Elvish Impersonators". ("Elvish Impersonators" is also an Ever Quest guild, though it's unclear if there's any causal connection between the two.)

Murphy's Rules (a compendium of nonsensical rules, funny errata and other game weirdness) included Elvish Presley in a list of annoying NPCs for players to encounter (along with Sailbad the Sinner and Uselysses).

In Discworld Noir, Lewton will say "Thank you very much" with an Elvis accent when a wizard informs him that glamours are "an elvish thing".

In Warhammer: Age of Reckoning, the player can grow Elvish Parsley.

In World of Warcraft, one April Fools joke introduced the Bard class - a new hero class which would attack enemies via Guitar Hero minigame. Had this actually been introduced, one could have expected to find lots of Night Elf or Blood Elf rockstars Bards. As a Shout-Out to this trope, the Bards on the World of Warcraft announcement were Blood Elves.

My Sims Kingdom. Forest Of The Elves. One is your classic wood elf, the other IS A ROCK STAR!!!

Webcomics

Larry's silly song in Veggie Tales's Lord of the Rings parody had him dressed as Elvis (and emulating his style) while singing a song about being in love with a girl who speaks Elvish. The reaction from the Legolas parody? "You're not a real elf! You're an Elfish Impersonator!"

Melfis, the leader of the Elves in the videogame of Faxanadu was in two episodes of Captain N: The Game Master. He shared some facial features (not to mention the wardrobe) of the singer, but with...blue skin.